I am in love with a chord. You hear it all the time in jazzy songs. It fits as a substitute for a number of chords, such as the IV or the iv minor or even the V. It’s built off the flat-VII chord, and it itself is a 7th with an added 10th and 13th.
Example: I’m dreaming of a white Christmas, in C major, when it goes - “may your dreams be merry and bright”:
Dreams be: I chord (C to Cmaj7).
Merry: V/IV chord (C7).
Bright: starts with IV chord (F).
then the A is flattened to Ab (iv minor chord, f minor).
And may all: “all” is back on the C chord.
but instead of that f minor, you can play this lovely smoochy Bb chord which is Bb, then the Ab above that, then the D above that and the G above that. x1x133
It’s also the 4th chord in the intro to Sister Sledge - We Are Family. What is it? I love it.